• Introduction
• What am I paying for?
• Opticians
• Your eye test
• Free eye tests
• Your prescription
• Definitions
• Everyday life & glasses
• Top tips

1. Download Guide PDF
2. Download Pocket Guide

Your prescription and what it means

On your prescription, as well as some basic details such as your name and date of birth, there will usually be a table that shows your prescription (see www.medicinenet.com/script/main/art.asp?articlekey=43046).

What the numbers mean

1. The first number is called the ‘spherical number’, and this will show whether you are short sighted (-) or long sighted (+) in each eye. A higher number means a stronger prescription.

2. If you have astigmatism (when the front part of the eye (the cornea) is the shape of a rugby ball instead of a regular circle), there will be a second and third number. The second number is the ‘cylinder number’, which can be negative or positive and measures the amount of astigmatism you have.

3. The third number is the ‘axis number’, which will be between 1 and 180. The axis number describes the curve in your eye.

4. Sometimes, you may have a muscle imbalance in your eye, so your optician will prescribe a prism and a prism base. The prism is usually written in fractions (for example 1 ½) and the prism base shows the direction of the prism in the lens (for example, IN, OUT, UP or DOWN). This is fairly uncommon so the boxes are normally empty.

You should also ask the optician for your pupillary distance (PD). Your PD is the distance between your eyes, measured between the centre of your pupils. If you have a high-strength prescription, it is more important that you lenses are centred more accurately. Usually, the optician will not add this to your prescription, so you should ask for it.

Now you are ready to look for the perfect frames, wherever that might be. Remember, you do not have to buy frames from where you had your eyes tested.